By Aimee Castor, DVM

City Cat Mobile Vet Service


Diabetes is caused by a lack of the hormone insulin which facilitates the utilization of blood sugar (glucose) by the body.  This results in an abnormal elevation of glucose in the bloodstream called hyperglycemia.

Signs often seen in diabetic cats:



Glargine insulin, when combined with a high protein/low carbohydrate diet, has actually cured diabetes in many cats.  That is, in newly diagnosed diabetic cats.  It has not been shown to resolve diabetes in cats that have had diabetes for a long time, but it of course is able to control it.

Glargine insulin is unfortunately expensive.  There is, however, a way to decrease the cost.  The bottle of glargine will expire after 6 months, but glargine pens will last up to 2 years unopened.  Consider contacting different pharmacies to determine if they will sell you single pen.  Then pens are usually sold in a bundle of 5 pens for approximately $350 to $400.  In the long run, purchasing the entire bundle will also be less expensive than buying a single bottle of glargine.  Each pen contains 3ml glargine and will last 3 to 4 months in the refrigerator after opened.  The pen is not as effective for giving insulin injections because the needle is too short and it injects it into the dermis rather than the subcutaneous tissue. We recommend that the insulin is drawn out of the pen with an insulin syringe and administered via the syringe.

Your cat will be started on insulin every 12 hours at an amount recommended by your veterinarian.  Never change this dosage without consulting your veterinarian first.

The scruff is now considered an inadequate place to inject insulin because it has a poor blood supply and therefore poor absorption capabilities.  The lateral thorax or abdomen is a much better site.  To achieve the best results, the injection sites should be rotated daily.Keep the insulin in the refrigerator, and to mix it, don’t shake the bottle, but instead, roll it between your hands.  Shaking the bottle will damage the insulin.If you are unsure if your pet received the full amount, don’t give a second dose.  It is better that the glucose be too high than too low.


In the past, diabetic cats were placed on high fiber diets but more recent information demonstrates that diabetic cats respond better to foods that are high in protein and low in carbohydrates.  Many canned foods are suitable for diabetes, even Friskies, due to the high protein content.  Dry foods, however, are completely inadequate, with the exception of Young Again.  Feed your cat 15 minutes before giving the insulin, and if your cat doesn’t eat, don’t give the insulin.

For a list of diabetic foods go to https://sites.google.com/site/felinehealthcare/home/recommended-foods-for-diabetes.


The other thing that you can do at home to evaluate your cat, is purchase Ketodiastix, small paper strips that contain reagents which change color indicating the amount of glucose and ketones in the urine.  They are easily obtained over the counter at human pharmacies.  Check your cat daily, preferably 1st thing in the morning, right when he/she urinates.  You can dip it into the wet spot in the litter box or catch your cat mid stream.  Keep a close watch on the results.  If they change, contact your vet.  If your cat is positive for ketones, and you are not able to contact your vet right away, go to the closest emergency clinic.  Ketones in the urine is very serious.


Hypoglycemia or insulin shock is when the blood glucose is too low.  As mentioned before, it is much preferable to have a glucose which is too high than too low.  Watch your cat closely for symptoms of hypoglycemia.

Signs of hypoglycemia:

If untreated, death can result.

If you see mild signs of hypoglycemia, give approximately 1 teaspoon of Karo syrup orally with a syringe or eyedropper and call your veterinarian.  If your cat is comatose, rub the Karo syrup on his/her gums, do not attempt to make your cat swallow it.  Contact your Vet ASAP or go to an emergency clinic.

For further information on feline diabetes go to the following website: www.felinediabetes.com